Where is the energy stored in adenosine triphosphate (ATP)?

Energy in adenosine triphosphate (ATP) is stored primarily in the phosphate bonds. ATP comprises three phosphate groups, and the bonds connecting these groups, particularly the bonds between the second and third phosphate (known as high-energy phosphate bonds), are where the energy is concentrated. When ATP undergoes hydrolysis—meaning it reacts with water to break the bond between the last phosphate group and the rest of the molecule—significant energy is released, which can be utilized for various cellular processes such as muscle contraction, nerve impulse propagation, and biochemical synthesis.

The ribose sugar and adenine base play structural roles in ATP but do not serve as sites for energy storage. Hydrogen bonds are involved in the interactions between ATP and other molecules but are not significant in energy storage. The understanding of energy storage in ATP is fundamental in biochemistry, particularly in energy transfer and metabolism within cells.